1. Field of the Invention
This invention relates to optically-active tartrate compounds, to methods of making such optically-active tartrate compounds and to the use of such optically-active tartrate compounds for the production of optically-active conversion products.
2. Prior Art
Due to the slight stability of the free group of acids, the racemic resolution of free carnitine causes difficulties; so the nitrile or the amides of carnitine are predominantly used for its racemic separation. For example, East German Pat. No. 23,217 teaches converting carnitine nitrile chloride, which has been converted by treatment with silver oxide into the hydroxide or by treatment with silver carbonate into the carbonate, with an optically-active acid into the diastereomers from which the suitable diastereomer is separated. The desired carnitine derivative is isolated from the suitable diastereomer. Another path, taught by Belgian Pat. No. 660,039, starts out from carnitine amide hydrochloride, which is converted with camphoric acid in the presence of AgNO.sub.3 into the diastereomeric mixture. The suitable diastereomer is again separated and analyzed.
However, the above processes have considerable disadvantages. Among such disadvantages is the difficultly-separable salt impurities obtained in large quantities, which make the dissociation of the racemate difficult. Also the numerous steps of the processes which are required to provide the carnitine amides, respectively, carnitine nitriles, accessible for the racemate dissociation make a technical or commercial application too expensive with regard to costs. These difficulties are increased, since as a result of the use of silver salts, one must operate with the exclusion of light in order to avoid any blackening of the reaction material.